SPEC stage 2 install results
Thread Starter
Racer
Joined: Feb 2008
Posts: 269
Likes: 0
From: Victoria British Columbia
SPEC stage 2 install results
Just one for the archives.
With a hoist it took my Dad and I 7hrs to re+re ; clutch, flywheel, tail shaft seal, rear main seal, trans and motor oil change. C4 Beam plates were added as well. The biggest pain was removal of the bell housing, the rest was pretty straight forward. Could have saved a lot of time if I had remembered to bring my service manual.
The clutch was a SPEC stage 2 matched with a single mass lightweight SPEC steel flywheel = approx $700
I'm still giving the clutch a bit of break in period but so far, compared to the stock set-up, it feels good. Although it does have a little more chatter.
The flywheel feels much better than stock in the way that it rev's faster, making RPM matched downshifting quicker. Maybe I'm imagining things but it seemed to be quicker to break the tires loose too. The big downfall is transmission noise. The conditions where I would usually be lugging the motor now have very loud transmission noise. Through regular acceleration it's only moderately louder.
The Beam plates were an easy install, and I think I can feel a difference in the way the car plants under acceleration but haven't had enough opportunities to really get into it.
Hope this helps someone I'll get part #'s if anyone is interested.
Cheers
With a hoist it took my Dad and I 7hrs to re+re ; clutch, flywheel, tail shaft seal, rear main seal, trans and motor oil change. C4 Beam plates were added as well. The biggest pain was removal of the bell housing, the rest was pretty straight forward. Could have saved a lot of time if I had remembered to bring my service manual.
The clutch was a SPEC stage 2 matched with a single mass lightweight SPEC steel flywheel = approx $700
I'm still giving the clutch a bit of break in period but so far, compared to the stock set-up, it feels good. Although it does have a little more chatter.
The flywheel feels much better than stock in the way that it rev's faster, making RPM matched downshifting quicker. Maybe I'm imagining things but it seemed to be quicker to break the tires loose too. The big downfall is transmission noise. The conditions where I would usually be lugging the motor now have very loud transmission noise. Through regular acceleration it's only moderately louder.
The Beam plates were an easy install, and I think I can feel a difference in the way the car plants under acceleration but haven't had enough opportunities to really get into it.
Hope this helps someone I'll get part #'s if anyone is interested.
Cheers
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
The noise is because of the low angle helical cut on the gears... all ZF6's make gear noise much like the old M22 4spd.
GM installed a 47LB Dual Mass FW at the factory to help act as a noise damper by increasing the roatating mass at the crankshaft and allowing inertia to smooth out the firing pulse of the engine. With a stock camshaft and the Dual Mass FW you can't hear anything.
However when you install a lightweight Single Mass FW, you loose all that inertia and even with a stock cam the ZF6 gets the "rocks in a tin can sound" at idle and under light acceleration. It's even worse with a big camshaft.
Will
Thread Starter
Racer
Joined: Feb 2008
Posts: 269
Likes: 0
From: Victoria British Columbia
There is nothing wrong with the brgs in his tranny.
The noise is because of the low angle helical cut on the gears... all ZF6's make gear noise much like the old M22 4spd.
GM installed a 47LB Dual Mass FW at the factory to help act as a noise damper by increasing the roatating mass at the crankshaft and allowing inertia to smooth out the firing pulse of the engine. With a stock camshaft and the Dual Mass FW you can't hear anything.
However when you install a lightweight Single Mass FW, you loose all that inertia and even with a stock cam the ZF6 gets the "rocks in a tin can sound" at idle and under light acceleration. It's even worse with a big camshaft.
Will
The noise is because of the low angle helical cut on the gears... all ZF6's make gear noise much like the old M22 4spd.
GM installed a 47LB Dual Mass FW at the factory to help act as a noise damper by increasing the roatating mass at the crankshaft and allowing inertia to smooth out the firing pulse of the engine. With a stock camshaft and the Dual Mass FW you can't hear anything.
However when you install a lightweight Single Mass FW, you loose all that inertia and even with a stock cam the ZF6 gets the "rocks in a tin can sound" at idle and under light acceleration. It's even worse with a big camshaft.
Will
Race Director
Joined: Sep 2001
Posts: 14,679
Likes: 752
From: NEwhere Ohio
I was very happy w my spec ststage kevlar clutch. It was a stage 2 that I bght/ instaled in 2002. What I liked about it was that it never lost that new clutch 'bite' to it. Right up until the day I blew out the center in it in the middle of 3rd gear at 110 mph. Wot.
Im now on a spec stage 3+. It has the same bite to it, and is supposedly beefier. Streetability is decent since its sprung hub and not a puck style.
I also did the lightweight al fidanza flywheel. Very happy. I enjoy the mild rattle during wot accel. Adds to the thrill. I don't notice any extra noise at idle.
Im really happy w. Spec.
Im now on a spec stage 3+. It has the same bite to it, and is supposedly beefier. Streetability is decent since its sprung hub and not a puck style.
I also did the lightweight al fidanza flywheel. Very happy. I enjoy the mild rattle during wot accel. Adds to the thrill. I don't notice any extra noise at idle.
Im really happy w. Spec.
Le Mans Master
Joined: May 2005
Posts: 7,355
Likes: 2,280
From: Central Maryland
I just wrapped up a nearly identical set of chores on my '94, except that I went with the Spec heavyweight steel SMF along with their Stage 2 clutch kit. I'm very pleased to be able to report zero gear rattle. I'd been a bit worried about this, as it was a problem that I really didn't want to have. The heavyweight SMF seems to have done the trick. The Stage 2 clutch has been operating superbly so far, though it's still in the break-in period.
Live well,
SJW
Live well,
SJW
Heel & Toe
Joined: Aug 2009
Posts: 20
Likes: 0
From: barboursville va
spec clutch
gosh must have been clutch week.. just installed spec 2+.. in my 88 original went 94K.. did not change the flywheel.. did have it turned.. really looking forward to going back to Summit Point.
Hey A Special shout out to Larry Da Saint and for the help...
Hey A Special shout out to Larry Da Saint and for the help...
Last edited by bodeane13; Nov 7, 2010 at 08:26 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: May 2005
Posts: 7,355
Likes: 2,280
From: Central Maryland
Presuming you're asking about the flywheel in the '94 that's mentioned in your profile...
No, the flywheel on the LT1 Corvette is not neutral-balanced. These engines are externally balanced. Call Spec for more info.
The aluminum flywheel will allow the engine to rev quicker, but will probably lead to significant gear rattle, and you'll need to work the throttle more to launch the car from a stop in normal street driving, as you'll have given away a lot of rotational mass, and the inertia it imparts. Either or both of these might or might not bother you, depending upon your personal preferences. I opted for Spec's extra-weight steel SMF to avoid these issues, and I'm pleased.
Live well,
SJW
No, the flywheel on the LT1 Corvette is not neutral-balanced. These engines are externally balanced. Call Spec for more info.
The aluminum flywheel will allow the engine to rev quicker, but will probably lead to significant gear rattle, and you'll need to work the throttle more to launch the car from a stop in normal street driving, as you'll have given away a lot of rotational mass, and the inertia it imparts. Either or both of these might or might not bother you, depending upon your personal preferences. I opted for Spec's extra-weight steel SMF to avoid these issues, and I'm pleased.
Live well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,355
Likes: 2,280
From: Central Maryland
I did mine on a Kwiklift, which is a step better than jackstands (and much safer), but even so it was not a job for the faint of heart.
If you're a decent mechanic, you can do it, but make sure you're properly equipped to take on the job.
You'll need to be able to safely raise the car to a workable height, you'll need a good selection of mechanic's tools, and a transmission jack is highly recommended (the ZF6 gearbox weighs somewhere around 145 pounds).
In addition to a jack for raising and lowering the gearbox, you'll also need a separate means of supporting the rear of the engine while the transmission is out of the car.
Air tools are perhaps not strictly required, but I wouldn't want to tackle the job without them.
And a Factory Service Manual is a must-have item, if only for the torque specs (but for much more also).
Live well,
SJW
If you're a decent mechanic, you can do it, but make sure you're properly equipped to take on the job.
You'll need to be able to safely raise the car to a workable height, you'll need a good selection of mechanic's tools, and a transmission jack is highly recommended (the ZF6 gearbox weighs somewhere around 145 pounds).
In addition to a jack for raising and lowering the gearbox, you'll also need a separate means of supporting the rear of the engine while the transmission is out of the car.
Air tools are perhaps not strictly required, but I wouldn't want to tackle the job without them.
And a Factory Service Manual is a must-have item, if only for the torque specs (but for much more also).
Live well,
SJW